US6270013B1 - Hand-holdable optical scanner particularly useful as electronic translator - Google Patents

Abstract

An optical scanner including a scanner head, a roller engaged by a record, the roller including optically readable marks, light sources and sensor which illuminate and sense both roller and the record, a lens for focusing light from the record onto the sensor, and a lens mirror for focusing light from the roller onto the sensor.

Description

This application is the national phase of international application PCT/IL97/00238 filed Jul. 14, 1997 which designated the U.S.

BACKGROUND OF THE INVENTION

The present invention relates to hand-holdable optical scanners for scanning record media. The invention is particularly useful in the optical scanner described in our Israel Patent Application No. 114,367 filed Jun. 27, 1995, and is therefore described below with respect to that application.

Our Israel Patent Application 114,367 describes a hand-holdable optical scanner for scanning printed text on record media and for simultaneously translating the words from one language into another, or from one definition to another in the same language. Critical requirements of such an optical scanner include compactness in construction and reliability in operation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an optical scanner which enables the scanner to be constructed very compactly, thereby making the optical scanner particularly useful, among other applications, as a hand-holdable electronic translator.

According to one aspect of the present invention, there is provided an optical scanner comprising a hand-holdable housing including: a scanner head for scanning a record medium; a roller engageable and rotated by the record medium when scanned by the scanner head, the roller including an optically-sensible marking for use in measuring the rotary movements of the roller; illuminating means for illuminating the record medium and the roller including the marking thereon; an optical sensor for sensing information on the record medium and the markings on the roller and for producing an output corresponding thereto; a first optical system including a focusing lens for focusing light reflected from the record medium onto the optical sensor; and a second optical system for focusing light reflected from the roller onto the optical sensor; the second optical system including the focusing lens of the first optical system but located at a shorter distance from the roller than from the record member; the second optical system further including a lens-mirror member having: a first face facing the focusing lens for receiving light therefrom reflected by the roller; a second face facing the optical sensor for transmitting light exiting from the lens-mirror member to the optical sensor; and a third, reflecting face for receiving the incoming light from the first face and for reflecting same through the second face to the optical sensor; at least one of the faces being light-converging to partially focus the received light such as to compensate for the shorter distance between the focal lens and the roller than between the focal lens and the record member.

The foregoing features enable the optical scanner to be constructed very compactly, more compactly than that described, for example, in our above-cited Israel Patent Application 114,367, since the single lens-mirror member used in the novel construction of the present application replaces two spaced-apart mirrors in the construction described in that patent application.

In the preferred embodiment of the invention described in the present application, the first face is the light-converging face, the reflecting face is planar, and the second face is also planar and is inclined so as to be substantially normal to the light received from the roller and reflected by the reflecting face through the second face.

According to an additional aspect of the present invention, the housing further includes an optical light guide for guiding the movement of the scanner head over the record medium, the optical light guide comprising a light source for projecting light laterally of the housing in the direction of movement of the scanner head over the record medium. In one described embodiment, the optical light guide further comprises a mirror within the housing for projecting a beam of light laterally through an opening in the housing in the direction of movement of the scanner head over the record medium. In a second described embodiment, the optical light guide further comprises a transparent guide member fixed to the housing; the transparent guide member having an inner surface exposed to the light of the light source within the housing, and an outer surface projecting outwardly of the housing in the direction of movement of the scanner head over the record medium.

According to a still further aspect of the invention, there is provided an optical scanner comprising a hand-holdable housing including: a scanner head for scanning a record medium; an optical sensor for sensing information on the record medium and for producing an output corresponding thereto; and a data processor for processing the output of the optical sensor; the data processor being programmed to first measure the output of the optical sensor when the scanner head is out of contact with the record medium to assure the output is below a first predetermined threshold, and then to measure the output of the optical scanner when the scanner head is in contact with the record medium to assure that the output is above a second predetermined threshold, before it processes the output of the optical sensor.

The foregoing features may advantageously be used in optical scanners for a wide variety of applications, but are particularly useful in hand-holdable electronic translators.

Further features and advantages of the invention will be apparent from the description below.

The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial illustration of one form of hand-holdable optical scanner constructed in accordance with the present invention;

FIG. 2 is a diagrammatic view more particularly illustrating the internal construction of the optical scanner of FIG. 1;

FIG. 3 is a diagrammatic front view illustrating the internal construction of the optical scanner of FIGS. 1 and 2;

FIG. 4 is a side elevational view of the roller in the optical scanner of FIG. 3;

FIG. 5 is a three-dimensional view of the lens-mirror member included in the optical scanner of FIGS. 1 and 2;

FIG. 6 is a diagram illustrating the optical path from the roller to the optical sensor including the lens-mirror member of FIG. 5;

FIG. 7 is a block diagram illustrating the electrical construction of the optical scanner;

FIG. 8 is a diagrammatic view illustrating a modification in the construction of the optical scanner of FIGS. 1 and 2 for purposes of incorporating an optical light guide to guide the movement of the scanner over the record medium;

FIG. 9 is a view corresponding to that of FIG. 8 but illustrating a modification in the construction of the optical light guide;

FIG. 10 is a top plan view of a transparent member in the guide of FIG. 9; and

FIG. 11 is a flow chart illustrating a procedure for detecting the contacting and the proper positioning of the optical scanner with respect to the record medium being scanned.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The electronic translator illustrated in FIGS. 1-3 of the drawings comprises a hand-holdable housing2 including ascanner head3 at one end for scanning a record medium, such as a printed text. An optical sensor, generally designated4, is enclosed withinhousing2 for sensing characters printed on a record medium RM scanned by thescanner head3 and for converting them to electrical signals.Housing2 also contains electrical circuitry, schematically indicated byblock5 in FIG. 3, which includes a storage device for storing a dictionary of words in one language and their translations in another language.Housing2 further carries avisual display6 for displaying the translations of scanned words.Electrical circuitry5 within the housing includes, in addition to the mentioned storage device, also a data processor for processing the electrical signals from theoptical sensor4, for recognizing words therefrom corresponding to words stored in the storage device, and for displaying their translations in thevisual display6.

Housing2 further includes four directional keys, generally designated7, for scrolling the words reproduced on thevisual display6; an ON/OFF key8 for energizing the scanner and for deenergizing it; and anEnter key9 for entering a word.Enter key9 may also function as a Continuation key, to be depressed when a word on one line is continued on a second line. The fourdirectional keys7 may be used for centering the words reproduced in thevisual display6, such that after a scanned word is centered in the display, theEnter key9 is depressed to display the translation.Enter key7 may also be used as a cursor to select a translation.

The scanner is powered by its own self-contained battery power supply, schematically shown at10 in FIG.3.

Theoptical sensor4 is constituted of a plurality of optical sensing elements arranged in a linear array perpendicular to the direction of movement of thescanner head3. In the example described below, it is a single linear CCD array of 64 pixels having a length of about 8 mm, and is used in three separate systems of the scanner: (1) a character detector system, for detecting the characters scanned by the scanner head; (2) a displacement detector system, for detecting the displacement or movement of the scanner head over the record medium; and (3) a record medium detector system, for detecting the proper positioning of the scanner head in contact with the record medium RM. The images produced by all three systems are focused by a common focusinglens11 on theCCD array4.

The character detector system includes alight source12 for projecting a beam of light onto the field of view of the record medium RM as it is scanned by thescanner head3. This light is reflected by the record medium RM back into thehousing2 and is focused by focusinglens11 onto theCCD array4. In order to prevent interference from visible light externally of the housing,light source12 is preferably a red LED.

The displacement detector system for detecting the displacement of the scanner head along the record medium RM includes a secondlight source14 which projects its light onto aroller15 engageable with the record medium RM, and rotated thereby as thescanner head3 is moved along the record medium.Roller15 is mounted for rotation about anaxis15aparallel to theCCD array4, i.e., perpendicular to the direction of movement of thescanner head3 along the record medium RM. This roller is provided with opticallydiscernible markings16 effective to reflect light fromlight source14 onto theCCD array4 corresponding to the rotary movements of the roller.

Roller15 carries fivelines16 each extending helically, between preferably tworeference lines17a,17b,for a fraction of the circumference of the roller and equally spaced from each other circumferentially of the roller. Alternatively, it is possible to use one reference line on theroller15. In FIG. 4 three of thelines16 are shown; the remaining two lines are located on the rear side of theroller15 and are not visible in the present orientation ofroller15. The tworeference lines17a,17bextend around the complete circumference of the roller at the opposite ends of thehelical lines16. The outer surface of theroller15 is black, but thelines16,17a,17bare white, or vice versa, so as to be visually discernible. Eachhelical line16 extends for substantially one-fifth the circumference of the roller, preferably slightly more than one-fifth to provide a small overlap.

Light source14 is preferably a source of visible light. It is projected onto the outer surface ofroller15 such that light will be reflected only from thehelical lines16 and thereference lines17a,17b.Thus as the roller rotates, a spot of light reflected fromhelical lines16 moves along the pixels of theCCD array4 such that the pixels illuminated by this moving spot of light track the displacement of the roller as the scanner head is moved across the record medium RM.

Since spots of light are also reflected from thereference lines17a,17b,the number of sensor elements spanned can be calculated and used to track the exact displacement position of the roller.

Due to the mechanical construction of theroller15, rotation of theroller15 may cause sideways movement of theroller15 through a small distance “d”, as illustrated in FIG.4. This sideways movement of theroller15 is compensated for by detecting the reflected light between the tworeference lines17aand17b.

As indicated earlier, focusinglens11 is used both in the optical system for focusing light reflected from the record medium RM onto theCCD array4, and also in the optical system for focusing light reflected from theroller15 onto theCCD array4. Since:

1/f=1/u+1/v

(wherein “f” is the lens focal length, “u” is the lens distance to the object, and “v” is the length distance to the CCD array) must be the same for both optical paths, and sinceroller15 is closer than the record medium RM to thelens11, the optical path from the lens to theCCD array4 for the light reflected from the roller must be increased.

This is accomplished in a very compact manner by the provision of a lens-mirror member21 in the roller optical path between thelens11 and theCCD array4.

Thus, as shown particularly in FIGS. 5 and 6, lens-mirror member21 includes anincident face21afacing the focusinglens11, an exitingface21bfacing theCCD array4, and a reflectingface21cfor receiving the incident light fromface21aand for reflecting it throughface21bto theCCD array4. Face21areceiving the incoming light reflected from theroller15 via the focusinglens11 is light-converging, i.e., convex, whereas the reflectingface21cis planar.Face21bis also planar but is inclined such as to be substantially perpendicular to the light received from the roller and reflected fromface21c.It will be appreciated that the same effect can be produced by making either face21bor21c,or both, light-converging.

Since thesame CCD array4 is used in the character detector system oflight source12 and the displacement detector system oflight source14, these two light sources are energized at different time periods to enable the data processor to distinguish between these two detector systems with respect to the output of theCCD array4. For example both light sources may be energized at the same frequency, e.g., 500 Hz, but at different time periods; alternatively,light source12 may be energized at a frequency of 500 Hz, whereaslight source14 may be energized at different time periods and at a higher frequency, e.g., 2 Khz. Preferably, both light sources are red LEDs, such that no filter is necessary, but could be of other types, e.g., infrared or ultraviolet, with or without filters.

FIG. 7 is a block diagram illustrating the overall electrical system in the above-described electronic translator. The electrical system includes adigital signal processor30 enclosed withinhousing2, as schematically indicated byblock5 in FIG.3.Processor30 receives inputs from the CCDoptical sensor4 after conversion to digital form by an A/D converter40.

Processor30 includes aCPU31 which controls the energization of the IRlight source12 used for character detection, and the visiblelight source14 used for displacement detection. These light sources are energized at different intervals and at different frequencies. Thus, when theCPU31 receives the output from theCCD array4 as a result of energizing the IRlight source12, it processes the information in acharacter detector system32; and when it receives the CCD array output as a result of energizing the visiblelight source14, it processes the information in adisplacement detector system33. The light received by the CCD array output fromlight source12 is also used in a recordmedium detector system34 for detecting the record medium RM.

Processor30 also includes an optical character recognition (OCR)system35 receiving the information processed in thecharacter detector system32 for recognizing characters. It further includes aPROM storage device36 for storing, in addition to its operational program, also a dictionary of words in one language and their translations in another language. It further includes aRAM storage device37 for use during the normal operation of the electronic translator. While thecharacter detector system32, thedisplacement detector system33, the recordmedium detector system34, and the optical character recognition (OCR)system35, are all shown as separate blocks in FIG. 7, it will be appreciated that they are actually logic units within thedata processor system30. Theprocessor30 also includes inputs from thecontrol keys7,8,9 illustrated in FIG.1.

FIG. 8 illustrates a modification in the construction of the optical scanner, to provide an optical light guide for guiding the movements of the scanner over the record medium RM. For this purpose, thehousing2 is formed with anopening50, and amirror51 is located within the housing for projecting light fromlight source12 out through opening50 laterally of the housing in the direction of movement of the scanner head over the record medium RM.

FIGS. 9 and 10 illustrate the optical scanner with another type of optical light guide, namely atransparent guide plate52 fixed to thehousing2 and extending laterally thereof at thescanner head3.Transparent guide plate52 is of semi-circular configuration. It has aflat edge52a,and a semi-circularouter edge52bextending externally of the housing laterally of thescanner head3 and formed with acursor line53 to guide the optical scanner over the record medium being scanned. Optionally,transparent guide plate52 may be illuminated by a light source, shown at12 in FIG. 9, within the housing.

FIG. 11 is a flow chart illustrating how thedata processor30 may be programmed to assure proper ambient light conditions, and also proper positioning of thescanner head3 in contact with the record medium RM, before processing the output of the optical sensor.

Thus, as shown in FIG. 11, the data processor is programmed to first measure the output of theoptical sensor4 to determine whether the output is below a first predetermined threshold corresponding to acceptable stray light conditions (blocks60-62). If the sensor output is above that threshold, this indicates that the scanner head may be pointed to a light source, a lit window, or the like, accounting for the excessive light received by the sensor.

If the sensor output is below the first predetermined threshold, the data processor then checks to determine whether the output is above a second predetermined threshold (blocks64-68); if so, this indicates that the record medium is in proper contact with the scanner head (block69), and therefore the data processor is enabled to process the character and position data outputted by the sensor (block70).

The flow chart illustrated in FIG. 11 includes an optional further step that may be performed in case the record medium is black and the data is white (rather than the usual reverse), in which case the output ofdecision block68 would be negative even when proper contact is made with the record medium. To anticipate this possibility, a check is made to determine whether theroller15 has moved (block80); if so, this indicates that the record medium and its characters are in the “negative print” form (block81); in such case, thedata processor30 is enabled to process the character and position data (block82), but the output of thesensor4 is inverted, to thereby invert the BIT map (block83) in view of this “negative print” condition of the record medium. In the present patent application the term “negative print” includes a text comprising “light characters” on a “dark background”.

When thescanner head3 is not in contact with a record medium, light source12 (for data detection) may be pulsed at a lower rate (e.g., 20 Hz). Light source14 (for position detection) may not be energized, or may be energized also at a very low rate for detecting “negative print” as described above with respect to FIG.11.

When contact with the record medium is detected as described above, the two light sources may be energized at the higher frequency described above, e.g., light source at a frequency of 500 Hz and light source at a higher frequency of e.g., 2 Khz. The two light sources are energized at different time periods to enable the data processor to distinguish between the two detector systems with respect to the output of the CCDoptical sensor4.

The optical scanner may be operated such that the data processing is automatically initiated when the scanner head is lifted from the record medium.

In the case of a word which is split to two lines connected by a hyphen, the scanner can be instructed not to begin the translation when the word portion of the first line has been scanned, but to delay the translation until the word portion in the second line has been scanned. This may be done in a number of ways, including the following: (1) Enter key7 (or another special key provided on the scanner) is to be depressed by the user and to thereby instruct the scanner to delay the translation until the word portion of the second line has been scanned; (2) the data processor recognizes the “hyphen” as an instruction not to begin the translation until the word in the next line has been scanned; or (3) the scanner is manually moved in the reverse direction to rescan, but reversibly, the scanned word of the first line, this rescanning being recognized as an instruction not to start the translation.

The accuracy of the scanner depends to a high degree on the accuracy of thehelical lines16 on theroller15. It is therefore highly desirable to pre-calibrate the scanner for each roller. This may be done by energizinglight source14 to illuminate the roller. Since there is an overlap between thehelical lines16, the CCD image sensor sees at least two spots corresponding to the distance between the two helical lines in any position of the roller. The number of pixel elements may then be counted spanning the two spots to provide a measurement of the distance between the two helical lines. This procedure may be repeated a number of times, and the average taken to provide a precise measurement of the distance between the helical lines.

While the invention has been described with respect to several preferred embodiments, it will be appreciated that these are set forth merely for purposes of example, and that many other variations, modifications and applications of the invention may be made.

Claims (10)

What is claimed is:

1. An optical scanner comprising a hand-holdable housing including:

a scanner head for scanning a record medium;

a roller engageable and rotated by said record medium when scanned by said scanner head, said roller including an optically-sensible marking for use in measuring the rotary movement of the roller;

an illuminator for illuminating said record medium and roller including said marking thereon;

an optical sensor for sensing information on the record medium and said marking on the roller and for producing an output corresponding thereto;

a first optical system including a focusing lens for focusing light reflected from said record medium onto said optical sensor; and

a second optical system for focusing light reflected from said roller onto said optical sensor,

said second optical system including said focusing lens of the first optical system;

said second optical system further including a lens-mirror member having:

a first face facing said focusing lens for receiving light reflected by said roller;

a second face facing said optical sensor for transmitting light exiting from said lens-mirror member to said optical sensor; and

a third reflecting face for receiving the incoming light from said first face and for reflecting same through said second face to the optical sensor;

at least one of the faces being light-converging to partially focus the received light such as to compensate for a shorter distance between the focal lens and the roller than between the focal lens and the record member.

2. The optical scanner according to claim1, wherein said first face is the light-converging face, said reflecting face is planar, and said second face is also planar and is inclined so as to be substantially normal to the light received from said roller and reflected by said reflecting face through said second face.

3. The optical scanner according to either of claims1 or2, wherein said housing further includes a guide for guiding the movement of the scanner head over the record medium.

4. The optical scanner according to claim3, wherein said guide comprises a light source located within said housing, and a mirror within said housing for projecting a beam of light laterally through an opening in the housing in the direction of movement of the scanner head to be moved over the record medium.

5. The optical scanner according to claim3, wherein said guide further comprises a transparent guide member fixed to said housing and including a cursor line extending in the direction of the scanner head is to be moved over the record medium.

6. The optical scanner according to claim5, wherein said guide includes a light source within the housing for illuminating the inner surface of said transparent guide member.

7. The optical scanner according to claim1, wherein said illuminating means comprises:

a first light source for illuminating said record medium;

a second light source for illuminating said roller;

and a control system for periodically energizing said first light source during predetermined times, and said second light source during other predetermined times, to enable said optical sensor to sense both the information on the record medium and the marking of the roller.

8. The optical scanner according to claim1, wherein said optical scanner includes a linear array of optical sensor elements extending parallel to the rotary axis of said roller, and said optically-sensible marking includes at least one line extending helically on the outer face of said roller.

9. The optical scanner according to claim8, wherein said roller includes at least one reference line extending around the circumference of the roller at the opposite ends of said helical line.

10. The optical scanner according to claim1, wherein said housing further includes electrical circuitry programmed to first check the output of the optical sensor when the scanner head is out of contact with the record medium to assure the output is below a first predetermined threshold, and then to check the output of the optical scanner when the scanner head is in contact with the record medium to assure that the output is above a second predetermined threshold, before the electrical circuitry processes the output of said optical sensor.

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